This invention relates generally to the field of mixing, and in particular to the mixing of fluids. In one particular aspect, the invention relates to the mixing of biological fluids within a chamber that is disposed within a heated environment.
Methods for using arrays of polymers to identify receptors with specific affinities for one of the polymers in the array are known. For example, one method uses immobilized antibodies to analyze binding to peptide ligands or vice-versa. Another type of method uses immobilized oligonucleotides to analyze hybridization to a target nucleic acid. For instance, U.S. patent application Ser. No. 08/624,312, filed Mar. 26, 1996, the complete disclosure of which is herein incorporated by reference, describes apparatus and methods for carrying out repeated hybridizations of a target nucleic acid to an array of nucleic acid probes. Such polymer arrays are described in, e.g., U.S. Pat. No. 5,143,854 and published PCT Application Nos. WO90/15070 and WO92/10092, the complete disclosures of which are herein incorporated by reference. These polymer arrays are nucleic acid arrays which include a plurality of different polynucleotides coupled to a substrate in different known locations.
In one exemplary arrangement, such arrays are packaged within a housing, like those described in, e.g., U.S. Pat. No. 5,945,334, and in copending U.S. patent application Ser. No. 08/624,312, previously incorporated by reference, Ser. No. 08/528,173, filed Sep. 19, 1995, now U.S. Pat. No. 6,140,044, and published PCT Application No. WO95/33846. The disclosures of all of these references are herein incorporated by reference. In brief, such a housing typically includes a body having a reaction cavity or hybridization chamber. The array or substrate is mounted over the cavity on the body such that the front side of the array substrate, e.g., the side upon which the polynucleotides are situated, is in fluid communication with the cavity. The cartridge includes inlet and outlet ports to allow various fluids to be introduced into and removed from the hybridization chamber.
During hybridization, it is often desirable to provide an efficient and effective way to mix the fluids within the chamber. This can be challenging since the chamber is typically in a temperature controlled environment, such as in an oven. Additionally, in at least one embodiment, the interior of the chamber is narrow, and it can be difficult to mix or agitate the fluid when within the chamber.
One exemplary technique for mixing fluids in a heated environment is described in copending U.S. application Ser. No. 09/032,724, filed Feb. 27, 1998, now U.S. Pat. No. 6,050,719 the complete disclosure of which is herein incorporated by reference. According to this technique, a set of cartridges may be positioned within an oven and then rotated to facilitate mixing of a fluid.
This invention is related to other techniques to facilitate the mixing of fluids which are held within a hybridization chamber to improve the hybridization process. The techniques of the invention are particularly well suited for mixing fluids within a temperature controlled environment, such as an oven.
In one embodiment, a mixing system comprises an elongate rotatable shaft having a rotational axis. A plurality of holding members extend radially outward from the shaft and are configured to rotate with the shaft. The system further includes a plurality of carriers that are insertable between two of the holding members. Each of the carriers includes a plurality of grooves, pairs of which are adapted to receive a cartridge having a chamber for holding a liquid. In this way, rotation of the shaft rotates the carriers about the rotational axis to mix the liquid within the cartridges.
In one particular aspect, a heating system may also be provided and comprises an oven having an interior and a motor. With such a configuration, the shaft may be horizontally disposed across the interior and coupled to the motor so that the motor may be employed to rotate the shaft. Further, a controller may be provided to control operation of the motor and the temperature within the interior.
In another aspect, the carriers may each comprise a carrier body having a bottom, a plurality of sides, an open top, and a projection extending from the sides. With such a configuration, the holding members may include slots for receiving the projections of the carriers. In this way, the carriers may simply be inserted into the slots.
In still another aspect, the grooves of the carrier are arranged such that the cartridges are parallel to each other when inserted into the grooves. In this way, multiple cartridges may be held within a single carrier. Conveniently, the grooves may be keyed such that the cartridges are insertable in only one orientation. In this manner, each of the cartridges will be similarly oriented to permit each cartridge to be rotated in the same manner.
Conveniently, a locking mechanism may be provided to lock the carrier to the holding members. As one example, at least one of the projections may include a knob, and the locking mechanism may comprise a biasing member that is received over the knob to lock the carrier to the holding member. Optionally, a plurality of holding bars may be positioned between the holding members. The holding bars may be configured to be placed adjacent a top end of the cartridges that extend above the top end of the carriers to hold the cartridges within the carriers when the shaft is rotated.
In another aspect, the slots in the holding members may be placed 90 degrees apart to permit four carriers to be held between two of the holding members. In one specific aspect, three holding members may be provided, with the middle holding member having slots for carriers positioned on opposite sides of the middle holding member.
Advantageously, the cartridges may include a pair of closely spaced apart walls that define the chamber, with the distance between the walls being less that the distance across either of the walls. With this arrangement, the carriers may be attached to the holding members such that the walls of the chambers are perpendicular to the rotational axis.
In another embodiment, a method is provided for heating and mixing a liquid. According to the method, a plurality of cartridges are provided that each have a chamber at least partially filled with a liquid. The cartridges are placed into grooves of a plurality of carriers, and the carriers are inserted between a pair of holding members that extend radially outward from a shaft having a rotational axis. The shaft is rotated to rotate the cartridges around the rotational axis. In so doing, the liquid within the chambers is mixed.
Preferably, the cartridges are also heated while rotating the shaft. For example, the cartridges may be rotated within a heated oven. In one aspect, the rotational axis of the shaft is horizontal during rotation. Such a configuration is particularly useful when the cartridges include a pair of closely spaced apart walls that define the chamber, with the distance between the walls being less that the distance across either of the walls. In this way, the carriers may be inserted between the holding members such that the walls of the chambers are perpendicular to the rotational axis. Further, the cartridges may include sides extending between the faces to further define the chamber, with the sides forming corners. As the carriers are inserted between the holding members, the corners are parallel to the rotational axis. In this manner, rotation of the cartridges agitates the liquid within the chambers as the flow of the liquid changes direction due to the change in direction of the sides.
In another aspect, the carriers each comprise a carrier body having a bottom, a plurality of sides, an open top, and a projection extending from opposite sides. In this way, the projections may be inserted into slots in the holding members. In still another aspect, the cartridges may be placed into the grooves of the carrier such that the cartridges are parallel to each other. Conveniently, insertion of the cartridges into the grooves may be prevented unless the cartridges are in a certain orientation. In this way, each of the cartridges will be inserted with the same orientation so that each cartridge will be rotated in the same manner.
In one particular aspect, the carriers are locked to the holding members to prevent their removal during rotation. Also, the cartridges may be prevented from sliding out of the carriers when the shaft is rotated.